There is known a busbar joint sleeve that includes a tubular case whose butt ends are closed with plates disposed outside the case. The plates have central openings, in which busbars are located, and the case has a chamber receiving contacts of the bars to be connected (Busbar joint sleeves, 35 kV phase-insulated busbar wireway, RAUTA-ENERGO).
There is known a transmission joint sleeve for electric cables that includes: an insulator made of an epoxy-based compound, the insulator fixed in a case made of a non-magnetic material, a plug-in connector, an additional insulator and a sealing assembly. The insulator is configured as a solid cast and is fixedly sealed to the case at one side thereof and slidably sealed to the case at the other side thereof. The insulator and the case are secured to each other by flange connections, wherein one of the connection contains a rubber gasket (RU147096U1, Oct. 20, 2014).
There is known a transmission joint sleeve for electric cables that includes: an insulator made of an epoxy-based compound, the insulator fixed in a case made of a non-magnetic material, a plug-in connector, an additional insulator and a sealing assembly, wherein the insulator is configured as a solid cast and is fixedly sealed to the case at one side thereof and slidably sealed to the case at the other side thereof. The insulator and the case are secured to each other by flange connections, wherein one of the connection contains a rubber gasket (RU2518192C2, Jun. 10, 2014).
There is known a device for coupling a high voltage electric cable having a paper insulator impregnated by an insulation fluid with a high voltage electric cable having a polymer insulator; the device includes a terminal sleeve disposed at the end of the paper-insulated electric cable, the terminal sleeve having a sealed busbar hinge insulator, wherein the joint area of the two high voltage electric cables is covered with an electric screen member and a case of the sleeve. The case is configured as an elongated integral part made of an elastic insulation material, the part having a through passage receiving the two high voltage electric cables. The case of the sleeve is equipped with electric adjustment funnels at its two axial ends, configured to receive the high voltage electric cables, wherein the funnels adjoin the conductive layers of the two high voltage electric cables when in the assembled position. The inner diameters of the through passage of the sleeve case at its two axial ends are configured to receive the high voltage electric cables and equipped with the adjustment funnels are strictly different according to the outer diameters of the high voltage electric cables, which outer diameters are different by at least 10 mm at the area of contacting the sleeve case (RU2009139673A, May 10, 2011).
There is known a joint sleeve for a busbar that includes: bearing bars located within insulation material of sidewalls which extend in parallel and define a receiving passage. A protective wire is preferably provided at the base of the busbar, while the protective wire is accessible from the receiving passage's side. The joint sleeve is substantially symmetrical relative to the middle cross-section plane thereof and includes contacts for connecting the bars of the busbar and mechanical guide parts and abutment parts of the joint sleeve which are configured to be inserted into the butt end of the busbar, thus providing limitation of the stroke thereof. The sleeve is characterized in that the contacts are provided in the form of L-shaped contact strips located correspondingly and configured to be spring-shifted within a region of the joint sleeve case across the longitudinal axis thereof. The contact strip has one side-projecting contact area located at one side of the middle abutment wall of the case and another side-projecting contact area located at the other side of the middle abutment wall which defines the middle cross-section plane or coincides with the same. The contact areas are located on the first L-shaped shoulder, wherein the side edge of the second shoulder of the contact strip adjoin the wall of the case made of an insulation material via a flat strap. The contact strips are made of a spring material and contain a slightly V-shape curved spring formed and orthogonally bent off the strip. The spring has a middle part with arms which ends are spring-loaded and adjoin the outer surface of the second shoulder of the contact strip, the surface being opposite to the projecting contact areas of the first shoulder (RU2013113959A, Oct. 10, 2014).
Patent documents also disclose joint sleeves including a case and electric contacts disposed therein (CN101465529A, Jun. 24, 2009; CN20135575Y, Dec. 2, 2009; JP2036717A, Feb. 6, 1990; U.S. Pat. No. 5,436,797; and JP2010110186).
The related art closest to the claimed joint sleeve is a known busbar joint sleeve, wherein the sleeve includes a hollow cylinder case made of a fiberglass plastic, the case having an electric contact secured to the wall in the central part thereof, the contact having outer and inner wires for equalization of electric field, wherein ring-shaped flanges made of aluminum are attached to the ends of the case, the flanges disposed at the outer surface of the case and connected to semi-rings having cradles engaging the current distributor sections. The outer surface of the case bears a layer of insulation paper on which a loop of the outer wire for equalization of electric field is positioned. A first copper foil layer is disposed on and soldered to the outer wire. A first aluminum copper foil layer is disposed over the copper foil layer and it presses the copper foil against the case. Some layers of insulation paper are wrapped over the first aluminum copper foil layer, while some layers of conductive paper are disposed between those insulation paper layers.
A second aluminum copper foil layer is disposed over the outer conductive paper layer along the whole length of the sleeve. A second copper foil layer is wrapped over the second aluminum copper foil layer along the whole length of the sleeve. An insulation paper layer is disposed over the second copper foil layer and a flexible heat-shrink tube is placed thereon, wherein the ends of the tube are placed on the sleeve flanges in an overlap manner and sealed. Two layers of a heat-shrink polyether jacketing tape is wound over the heat-shrink tube in an overlap manner. Threaded holes are disposed in each flange, the holes adapted for providing vacuum in between the sleeve case and the heat-shrink tube and for allowing pumping epoxy resin into the insulation layers of the sleeve. All those layers and gaps between the layers and the heat-shrink tube are filled with cured epoxy resin and all those layers are disposed along the length of the sleeve between the flanges thereof. A protective aluminum or steel tube is placed over the heat-shrink tube and protective silicon caps are provided at the ends of the protective tube. The caps are equipped with clamps for connecting the protective tube to the busbar sections. The inner wire of the contact is placed within the chamber of the sleeve case in order to connect the contact to the conductive bar of the busbar, whereas the outer wire is placed outside the sleeve case and is pressed thereto by the layers of the sleeve (RU2439764C1, Jan. 10, 2012, the closest prior art).
The common features of the known sleeve and the two embodiments of the claimed sleeve are as follows. Each of the sleeves includes a tubular metal case including an insulated supporting tube made of paper impregnated with cured epoxy resin. A grounding screen is disposed inside the metal case and is secured to the supporting tube and wraps around it. The butt ends of the metal case are occluded with flanges each having a central hole for a busbar disposed therein. The case and the flanges are made of a non-magnetic metal material (RU2439764C1, Jan. 10, 2012).